Positive variable speed drive



Nov. 5, 1940. E. F. KERKHOFF 2,220,343

POSITIVE VARIABLE SPEED DRIVE Filed April 27, 1939 3 Sheets-Sheet 1 2:9-I I/vvE/w'oe [DA/A599 f. KER/(Hoff;

1940- I E. F. KERKHOFF 2,220,343

PbSITIVE VARIABLE SPEED DRIVE Filed April 27, 1939 3 Sheets-Shed; 2,

.447 TOP/v5 r5 Patented Nev. 5, 1940' UNITED STATES PATENT OFFICEPOSITIVE VARIABLE SPEED DRIVE Edward Kerkhofi, Indianapolis, Ind.

Application April 2'7, 1939, Serial No. 270,314

2 Claims.

This invention relates to a positive variable speed drive wherein theremay be no slippage between shiftable elements within the drive. I amaware of the fact that variable speed drives have been proposedheretofore wherein two opposing disks, one a driving disk and the othera driven disk, were frictionally interconnected by one or moreintervening rollers contacting the two disks with considerable pressureso that the drive from one disk to the other would be taken through suchrollers dependent upon friction. Also I am aware that in some casesthese disks have been provided with annularly disposed teeth in steps tohave the intervening roller also toothed to be shifted from one step tothe other.

In my invention, however, I propose to employ a continuous tootharrangement whereby as the intervening element is shifted, it will bemaintained in constant mesh with the teeth of the two opposing disksregardless of this degree of shifting so thatthere will be at all timesa positive drive from one disk to the other.

An important advantage of the invention resides in its extremesimplicity with a minimum number of parts insuring a calculable drivenspeed when the driving speed is known.

These and other important objects and ad- ,vantages of the inventionwill become apparent to those versed in the art in the followingdescription of one particular form of the invention'as illustrated inthe accompanying drawings, in which 7 Fig. 1 is a side elevation inpartial section of a structure embodying the invention;

Fig. 2, a central, vertical, longitudinal section;

and

Fig. 3, an elevation of the tooth side of one of the major disks.

Like characters of reference indicate like parts throughout the severalviews in the drawings.

I form a central ring housing In to be supported in any suitable mannersuch as by the pedestals II and I2. A spider l3,- herein shown as havingthree legs, is entered from one side 4,; of the housing to have each legkeyed through a key I! to the housing ring to maintain the spider infixed position in relation to the ring.

A plurality of spur gears I5, herein shown as three in number, arerockably carried between 50' each of the adjacent legs of the spider l3.As indicated. in Figs. 1 and 2, each spur gear I5 is mounted upon anaxle l6 which'is supported by and free to turn in trans verselypositioned bearings l6 and I! provided by the gear carrier I8.

55 The carrier l8 has end trunnions l9 and 28 rotatably carried inbearings extending from the legs of the spider I3, so that the carrierI8 is free to rock on an axis perpendicular to the plane of the gear I5while the gear I5 is free to turn through its axle 46 on an axis passingthrough 5 the center of the spider.

The degree of rotation of the carriers I8 is determined by a simpleexpedient. Each of the carriers I8 carries an inner gear' segment 2|which is in constant mesh with a centralspur o gear 22 that is carriedon a stub shaft 23, herein shown as an integral part of the spider I3.

By this means, all three carriers I8 are fixed in position, one relativeto the other. The teeth on the gear segments 2| and on the gear 22 15are arranged to be such that when one of the carriers I8 is rocked, itsgear segment will revolve the spur gear 22 about its shaft 23 andthereby in turn rock the other two carriers accordingly. 20

In the form herein shown, the upper gear I5 is horizontally disposed andits carrier I8 carries a second gear segment 24 which is in constantmesh with the teeth of a rack gear 25.

This rack gear 25 is slidingly guided through a 25 I slot in the floorof a cap 26 which is mounted on an upwardly extending part of thehousing ring I0. An eye 21 extends upwardly from the rack gear 25 tohave a screw-threaded shaft 28 pass therethcrough in screw-threadedengage- 30 ment. This shaft 28 has trunnions 29 and 30 of reduceddiameters at its respective ends carrying appropriate thrust bearingsand radial bearings whereby rotation of the shaft 28 through theexternally projecting trunnion 30 will turn 85 the shaft 28 and therebyadvance or retract the eye 21 to carry the rack gear 25 to and froacross the gear segment 24. The teeth are diagonally positioned asbetween these two gear members so that the movement of the rack gear 25will 40 cause rotary movement of the gear Segment 24 and thereby shiftnot only the top carrier l8 but also the other two carriersinterconnecting therewith through the spur gear 22. Preferably a spidercover 3t is provided to engage over the stub shaft 23 and provide anabutment for the gear 22 so as to maintain that gear in a centralaligned position.

A disk-like member 32 is provided with a stepped shaft 33 to carry asuitable bearing, herein shown as a ball bearing 34, capable of takingand thrust, and an outer oil retaining packing ring 35. A housing endplate 36 is formed to fit around the outer side of the housing ring land carry the bearing 34 as well as the packing 35.

This disk member 32 is preferably provided with a central bore 31 withinwhich is carried a bearing, herein shown as a ball bearing 38, thatreceives a stub shaft 39 extending integrally from the spider coverplate 3|.

On the inner face of the disk 32 is formed an annularly depressedportion, the arc of this depressed portion being a part of a circlewhose center would be at the exact center of any one of the gears l5.This concave annular portion is not left smooth but is cut to form teethin the nature of a spiral gear although at any point on any one of theteeth so cut the thickness of the tooth is constant and the distanceapart of the teeth is constant in respect to all of the other teeth whenmeasured at any point normal to a tangent at that point. These teeth arecut by revolving the disk 32 on its own axis through'the center of theshaft 33 while a cutter is revolved on the axis of the gear l5, the axisof the cutter being rocked in parallel relation to the disk 32 duringthe cutting operation. This will give a longitudinal curving of tooth asindicated in- Fig. 3 wherein the ends of the teeth as appearing at thecentral part of the disk 32 will have narrower terminal cross sectionson the gear face than they will have at the outer tooth ends by reasonof the difference in angularity of the teeth as between those twolocations, assuming that the cutter revolves once on its axis while thedisk makes one revolution. Different angularities of the disk teeth willbe had by varying this relative speed and rocking of the cutter. Thecentral area peripherally bounded by the inner terminal endsof the teethhas a diameter preferably made to equal the distance from thatperipheral boundary to the outer peripheral boundary of the terminalends of the teeth at the outer end of the annular channel.

A second disk member 40 has an integrally extending stepped shaft 4|supported by a thrust ball bearing 42 carried in the opposite end plate43 that is fixed to the other side of the ring housing ID. The innerface of this disk 40 has a counterbore in which is positioned a ballbearing 44 that centrally receives the stub shaft 45 that extendsintegrally and centrally from the side of the spider I3. The two shafts33 and 4| are axially aligned one with the other and the disks 32 and 40are carried into meshing engagement on the opposite respective sides ofthe intervening gears IS. The disk 4|! has its teeth disposed inopposite angular relation to the teeth of the disk 32.

Now assuming that the shaft 33 is the driving shaft, and that the gearsl are each positioned as indicated in Figs. 1 and 2, those gears will beturned by reason of their meshing with the disk teeth and will cause thedisk 40 to be revolved in the opposite direction at the same speed asthat of the disk 32 to in turn cause the shaft 4| to turn at the samespeed as that of the shaft 33. By operating the extending trunnionmember 30 to shift the rack gear 25 and rock the carriers of the variousgears l5, the right-hand side bf the upper gear I5, Fig. 2, may bedropped to cause the other side to be raised. The other gears would, ofcourse, be correspondingly shifted.

Then thespeed of the disk 40 is decreased in relation to the speed ofthe disk 32. Of course, the opposite condition may prevail by shiftingthe gears l5 accordingly. Therefore, it is to be seen that as the gearsl5 may be shifted into positions to bring their peripheries nearer thehub of one disk and nearer the periphery of the other, a variation inspeed between those two disks will be obtained, all without disengagingthe intervening gears I5 from the teeth of the two opposing disks. Thisis made possible by the peculiarly formed teeth in the concave portionsof the opposed disks.

While I have herein shown and described my invention in the one bestform as now known to me, it is obvious that structural changes may beemployed, such, for example, as in the particular means for shifting thegears Hi, the means for mounting the opposing disks, and the like, allwithout departing from the spirit of the invention and I, therefore, donot desire to be limited to that precise form beyond the limitations asmay be imposed by the following claims.

I claim:

1. A pair of axially aligned, spaced apart shafts, a driving memberfixed to one shaft, a driven member fixed to the other shaft, each ofsaidmembers having an opposing groove therearound, the cross-sectionalcontour of each of which grooves constitutes an arc of a common circle,both of said grooves being provided with substantially spiral teethacross their faces, means maintaining both of said members a fixeddistance apart, at least one spur gear between said members to haveteeth on the spur gear in constant mesh with both the driven and drivingmember groove teeth, a spur gear carrier on which the spur gear mayrotate about its own axis, the line of said axis being angularlydisposed to the axis of said shafts and remaining in a plane includingthe shaft axis, and means for rocking said carrier to shift said spurgear axis within said plane whereby a positive Worm type drive is hadwith an infinitely variable speed ratio between said driving and drivenmembers without shifting apart of those members.

2. A pair of axially aligned, spaced apart shafts, a driving memberfixed to one shaft, a driven member fixed to the other shaft, each ofsaid members having an opposing groove ther'earound, the cross-sectionalcontour of each of which grooves constitutes an arc of a common circle,both of said grooves being provided with substantially spiral teethacross their faces, means maintaining both of said members a fixeddistance apart, at least one spur gear between said members to haveteeth on the spur gear in constant mesh with both the driven and drivingmember groove teeth, a spur gear carrier on which the spur gear mayrotate about its own axis, the line of said axis being angularlydisposed to the axis of said shafts and remaining in a plane includingthe shaft axis, and means for rocking said carrier to shift said spurgear axis within said plane whereby a positive worm type drive is hadwith an infinitely variable speed ratio between said driving and drivenmembers without shifting apart of those members, said spiral teeth beingof that shape and angle as are produced by a revolving cutter on thespur gear axis simultaneously with rocking of the axis in said plane theteeth being thereby shaped to permit said spur gear rocking while inconstant mesh therewith.

- EDWARD F. KERKHOFF.

